Preventing Wax Deposition in Crude Oil Using Polyethylene Butene and Nano Zinc Oxide

Abstract

This research examines the use of 75nm Zinc Oxide nanoparticles (Nano ZnO) and Polyethylene Butene (PEB) in reducing the viscosity of Nigerian waxy crude oil. The rheology of the crude oil was studied by measuring the viscosity and shear stress of crude samples contaminated with varying concentration of PEB (500ppm, 1000ppm, 2000ppm, 3000ppm, 4000ppm and 5000ppm), varying concentrations of Nano ZnO (1wt%, 2wt%, 3wt% and 4wt%) and different blends of PEB and Nano ZnO at temperatures of between 10°C to 35°C and shear rates from 1.7 to 1020s-1. From Rheological Modelling analysis conducted, the Power law pseudoplastic model was the best fit for the experimental data with a regression coefficient of 0.99. Analysis of crude sample before addition of inhibitor showed evidence of non-Newtonian fluid behaviour as the shear stress-shear rate relationship curves were nonlinear due to wax precipitation at low temperatures (10°C to 15°C). The waxy crude demonstrated shear thinning behaviour with increasing shear rates (increasing turbulence) and the viscosity reduced with increasing temperature. The addition of inhibitors (PEB, Nano ZnO and their blends) effected Newtonian fluid behaviour in the crude samples as the shear stress-shear rate relationship curves were linear at all temperatures under study. The optimum concentration of the inhibitors in this study is 2000ppm PEB (causing 33% viscosity reduction) and 1wt% Nano ZnO (effecting 26% viscosity reduction). The best concentration of the blend was 2000ppm PEB blended with 1wt% Nano ZnO which effected a viscosity reduction of 41%. The research demonstrates the novel application of the blend of Nano ZnO and PEB in improving flowability of Nigerian waxy crude oil especially in offshore conditions with prevailing cold temperatures.